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Title: The nucleoprotein of calf thymus glands : the reaction of mannose with glucosamine hydrochloride
Author: Murray, Kenneth
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 1959
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Part One Preparations of nucleoprotein having reproducible characteristics were obtained from calf thymus glands by a mild extraction procedure. A preliminary examination of the dissociation of the complex was made and its physico-chemical behaviour was investigated in relation to that of its nueleic acid component. The nucleoprotein was highly aggregated in solution at low ionic strength, but at high ionic strength a weight-average molecular weight lower than that of nucleic acid itself provided additional evidence for the dissociation of the nucleoprotein. Spectrophotometric studies showed that the nucleoprotein was denatured by heat and by alkali in a similar manner to nucleic acid, although denaturation by heat was slightly retarded. The spectrophotometric titration behaviour of the two substances was almost identical, but their potentiometric titration curves differed significantly. Nucleoprotein solutions exhibited the features of nucleic acid devolving from its unique helical structure, indicating that this structure is retained by the nucleic acid within the complex. Part Two A general reaction has been discovered between amino sugars and aldoses for which the essential requirements are a free amino group and an aldehyde group. Three compounds (A, B and C) were separated by ion- exchange chromatography from a mixture obtained by heating D-mannose with D-glucosamine hydrochloride. Compound B was identified as 5-hydroxymethyl furfuraldehyde (HMF) from its ultra-violet absorption spectrum, chromatographic behaviour, and distribution coefficients between two different solvent systems, and was characterised as its 2:4-dinitrophenylhydrazone. Compound A was very unstable and was hydrolysed by cold water to mannose (characterised as its p-nitranilide) and glucosamine (characterised as its carbobenzoxy derivative). On heating in aqueous solution, the hydrolysis was accompanied by degradation to HMF (characterised in the same way as compound B), and the formation of melanoidins. The HMF isolated from the reaction mixture was shown to arise from compound A and C14-HMF was obtained when the condensation was effected with a mixture containing C-mannose and glucosamine hydrochloride, showing that the HMF originated in the mannose moiety of compound A. From these and other experiments, the structure N-mannosyl-glucosamine was assigned to compound A. Compound C was stable in aqueous solution, and hydrolysis with acid gave equimolecular quantities of mannose and glucosamine hydrochloride, but was not accompanied by a browning reaction. On the basis of periodate oxidation experiments, its behaviour in the Elson-Morgan reaction, and a number of other colour tests, compound C was provisionally assigned the structure 6-O-α-D-mannosyl-Z-amino-2-deoxy-D-glucose. Certain aldehydes were found to behave as bases on a sulphonated polystyrene resin. This interesting discovery may provide the basis of a new method for the separation and analysis of aldehyde mixtures.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QH Natural history ; QP Physiology